Unlike most Android OEMs, Apple does not include battery capacities in its spec lists for iPhones. However, it may be a particularly pressing issue this year, as the new 12 series has gone 5G, something that may eat screen-on time. A Dutch carrier has listed actual milliamp-hour figures for all 4 variants, and they make for worrying reading.
https://www.notebookcheck.net/The-iPhone-12-series-battery-sizes-are-listed-in-full.498385.0.html
2227 for 12? Impressive if true, at least when compared to the SE20 with only 1821.